1. Field of the Disclosure
This disclosure relates to a liquid crystal display (LCD) device, more particularly to a back light unit adapted to simultaneously prevent an assembly fault and brightness deterioration, and an LCD device including the same.
2. Description of the Related Art
Nowadays, LCD devices are gradually being used in a wide range of applications. This results from the fact that LCD devices have features, such as light weight, thinness, low power consumption, and others.
The LCD device is generally configured with a liquid crystal panel and a back light unit applying light to the liquid crystal panel. The liquid crystal panel includes a liquid crystal layer interposed between two substrates. Such a liquid crystal panel changes the direction of liquid crystal molecular alignment and causes regional differences in the transmittance of light passing through the liquid crystal layer. The regional transmittance differences allow an image to be displayed on the liquid crystal panel. However, the liquid crystal panel cannot emit light for itself Due to this, the LCD device requires a back light unit disposed at a side of the liquid crystal panel and configured to apply light to the liquid crystal panel.
The back light unit may include a reflective sheet, a light guide plate, a light source unit, a bottom case and a support main. The bottom case is used to accommodate the reflective sheet, the light guide plate and the light source unit. The support main is combined with the bottom case. Moreover, the back light unit may include both light source units each of which is disposed on both side surfaces of the light guide plate, in order to realize high brightness.
In order to assemble such a back light unit, two light source units are first placed within two opposite sides of the bottom case, respectively, and the reflective sheet and the light guide plate are sequentially disposed inside of the bottom case provided with the light source units. Then, the bottom case is engaged with the support main.
More specifically, the light guide plate is disposed between the light source units which are positioned inside of the bottom case. As such, the light guide plate may be disposed to contact the light source units at both sides of the guide plate. Due to such contacts, the light source units may be damaged and/or the light guide plate may also be damaged or deformed. To solve this matter, a fixed distance between the light guide plate and the light source units is kept by either reducing the size of the light guide plate or shifting the light source units toward the side walls of the bottom case beyond designed positions of the light source units. In other words, an assembly tolerance is provided between the light guide plate and the light source units in order to prevent an assembly fault of the back light unit. However, the assembly tolerance still causes light leakage and further deteriorates brightness of the back light unit.
In view of the above, there is a need for an alternative way to simultaneously prevent an assembly fault and brightness deterioration of the back light unit.